Birty Dastards Jeep Club
Tech Forum => Workshop => Topic started by: JamesH on December 04, 2013, 11:32:32 AM
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Need help on the question that's probably lost in my build thread (see below): Is it likely to be the cheapo TPS I fitted and should I get a Mopar one? Or could it be another sensor or something mechanical? It's really pissing me off now :011:
Question - bad idle, really bad splutter / hesitation, TPS changed, no blocked CAT, crank and cam sensors replaced not long ago with Mopar ones. No fault codes last time I scanned but I didn't scan again today. Ignition components not old and v low miles on them. Won't rev above 3k rpm. Has moments of perfect idle but it's not driveable. Should I start looking at mechanicals? Compression?
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Two TPS and the throttle body from me no good? Oh dear :icon_redface:
Got mine from Lighties as they now do one that they guarantee.
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Two TPS and the throttle body from me no good? Oh dear :icon_redface:
Got mine from Lighties as they now do one that they guarantee.
Wrong connectors for my XJ unfortunately. Interesting about Lighthouse, maybe worth giving them a call.
From being in the Jeep at Cheapfest you almost immediately said it was likely to be TPS so that's the direction I've been heading, now I'm just worrying it's something else and maybe more difficult / sinister :jpshakehead:
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Rock auto mate ?
Your RockAuto discount code 1770003515075638 will expire on December 8, 2013.
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Funny that... Lighthouse sold me crown and told me it wouldn't work then got me a mopar one that did...
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Is it worth speaking to them then?
The dealer will take weeks, Rockauto are quick but probably just Crown and equivalents. Lighthouse do next day if it's in stock
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Rockauto will give you a list of manufactures and quick, my O2 sensors were here within 48hrs plus cheaper even after taking postage into account, just be aware that if you order more than 1 item that they come from the same warehouse or you get 2 transport charges
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Rock Auto.
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I'm a big Rockauto fan but they don't do a Mopar TPS and I've already bought an aftermarket one that has made no difference (possibly worse).
I tried Lighthouse by no answer so I think I'll call them tomorrow and discuss the issues and maybe they can get me a Mopar one like they did for j33pky.
j33pky - any idea or explanation why the Crown one wouldn't work?
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Andrew said they were hit or miss... Or shit. £115 ish for a mopar one
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But it worked straight out of box
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Do you get JP magazine the symptoms you describe are an exact match to those that they describe for the MAP sensor
the article is called driveway diagnostics
they even say that it wont through fault codes
have a look at their website
I'll scan the article tomorrow just in case
Regards tim
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Worth a try I suppose Tim, thanks.
Any electrickery gurus know if I van test the sensors and how - I have multimeter and obd2 scan tool but no oscilloscope.
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I'd also look at upstream and down stream o2 sensors....
can you not splice the wildwood tpa onto your xj harness? i had to do this a lot on my engine swap, the plugs were different between years
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I have a spares one of each taken from XJs .If you want them for the postage (plus a beer) I will send them to you. I took them from the scrappys for my ZJ which was cured of similar faults by replacing the MAP sensor.
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Mike - Sounds good, can you check if they have round or flat pins for the connectors first please?
Will, I could yes but I'd need the correct plug or would be bodging with electrical connectors and tape. I might do something like this just to test it. Unless I'm being dumb about it of course and missing the easy way to do it.
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if theres just 2 wires a multimeter should show if theres any dead spots just set it to resistance. cheapo analogue meters work best .
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The TPS has three connections on it
a pos one side neg the other and the centre is the variable one.
put a meter between the centre and neg move the throttle and the voltage should change with the trottle
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Ah. I have it a bit confused. You need the sensor and flying lead
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The TPS has three connections on it
a pos one side neg the other and the centre is the variable one.
put a meter between the centre and neg move the throttle and the voltage should change with the trottle
Tested this morning - got nice steady increase in signal voltage from 0.6v - 3.8v closed to open with no obvious blank spots using a digital multimeter and opening the throttle very gradually and allowing the meter to register.
Do you know if the voltages are correct? The supply voltage is 5v and disconnected the signal wire has 4.6v
My instinct is that this is ok and that I should change the map sensor but reassurance would be nice.
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The signal voltage is 12 to 76% of the 5V supply which is fine. My scan gauge shows mine as 14 at idle and 74 at WOT.
Since 98 models have just one upstream O2 sensor you can disconnect it. That will force the computer to use it's programmed fuel tables. If it runs OK with the sensor unplugged the sensor is usually (99%+) the cause of the problems.
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Is the one on a 98 TJ the same ?
If I can find my spare, I'll bring it to TH
We replaced the 2 oxygen sensors, TPS & cleaned up the contact to the fuel tank at the fuel tank end, got rid of all our rough running, o2 sensors seemed clean enough so cant be 100% what was the problem or a combination
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Hi James
heres the pdf's
if you look at the last caption it describes you issue perfectly
Regards Tim
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Excellent work guys, MAP sensor ordered as it seems highly likely to be causing the problems and that description of the crap running from the JP article is exactly my symptoms.
The 02 sensors aren't old and the symptoms are worse than when I had problems with the original one before and replaced it but I may come back to this if the MAP sensor doesn't fix it.
Gaz - sensors are probably the same, mine is a 98 and has flat blade connectors for all the sensors - other Jeep connectors are round pin connectors. The replacement TPS seems fine, O2 sensors are unlikely to be the prob just cos they are newish and I've only just removed the fuel tank pump assembly and cleaned it all up (but I could have damaged something re-fitting it of course!
I'll report back as soon as the sensor gets here and I can fit it.
Thanks again, I owe you all a few beers for chipping in with the advice.
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Mike - Sounds good, can you check if they have round or flat pins for the connectors first please?
Will, I could yes but I'd need the correct plug or would be bodging with electrical connectors and tape. I might do something like this just to test it. Unless I'm being dumb about it of course and missing the easy way to do it.
The TPS have flat pins.
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Mike - I got over excited and ordered a new MAP sensor. If you want some beer money for them I'll still take them for spares and to test on my Dad's XJ that is running a bit crap.
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98 TJ/XJ 4.0 O2 sensors are the same. What brand sensors are currently fitted? Jeeps don't seem to like Bosch in general, though I've used them in the past without problems.
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New MAP sensor fitted, Jeep started and died a couple of times and now won't start. Re-fitted old sensor, still won't start. Fuel gauge and voltmeter don't register when ign turned on. Codes P1698, P1694 and P1685 stored. The first 2 are communication probs in the sensor circuit / BUS, the last is SKIS related :die:
I've read a lot of ideas for next checks but thought I'd post this update just in case anyone had experienced this and can describe the fix.
Chances are it's a wiring or ground fault somewhere but where to start :017:
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After 2 hours of pissing about with a multimeter I've concluded it's fooked :banghead:
I've got odd readings, fuses with no power to them and error codes but don't know what it all adds up to.
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Nightmare James, I feel your pain but I know you'll sort it..
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If the SKIM detects an invalid key and you start the engine a couple of times and it kills it after 3 secs does it then lock the PCM in some way to the point where it will crank but not fire?
The keys are fine but I have a fault codes for SKIM reading invalid key so thinking maybe the module is shagged and thinks I'm stealing the Jeep.
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Had a similar problem with the zj
The imobiliser had a fault and need to be replaced
Some times leaving the bat disconnected for a day ment it worked for a bit
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Was it the immobiliser module in the steering column?
When it went did the Jeep just crank but not start? Any other symptoms?
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it was the black box behind the light switch on the zj
the ZJ started but would only run when you rev ed it then stopped turning over
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Useful to know. Did you replace the box and have to get the PCM re-programmed by dealer (or someone else?). Do you have the grey transponder key and SKIS or the other immobiliser type?
Questions, questions, sorry :icon_biggrin:
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It was 9 years ago and the box was replaced by a auto electrician person but kept the keys
sorry its a bit vage
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here's a thought have you checked your neutral safety switch
as my bro as a similar prob with the jeep would not crank
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Bla Bla Bla all I'm hearing is "fook it I'll fit a lexus v8" It will solve the starting problems :lol_hitting:
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here's a thought have you checked your neutral safety switch
as my bro as a similar prob with the jeep would not crank
Jeep cranks fine in P and N just no start and diagnostic codes for SKIM invalid key and 2 CCD-bus non communication codes.
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Owt to do with the skis system is a head fuck.
I wish you luck,sir.
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Bla Bla Bla all I'm hearing is "fook it I'll fit a lexus v8" It will solve the starting problems :lol_hitting:
:003:
If I can't even fix this electrical problem just imagine all the tech threads I'll be starting if I try and wire one of those up
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go on fit a Lexus V8 you know you want to
watch the Old iron crews implode heads in
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I had a very similar issue on my old XJ, SKIM code, no starting, power not where is was expected in the relay box, despite not throwing any CPS codes it was the CPS. Trying to remember why I changed it, was result of no power to one of the relays which could only be because of a bad CPS. Can you scope it when its cranking to confirm its good?
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:imwitstupid:
thats a good point as the CPS could be confusing the ECU
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I have an old CPS that I changed because I melted the wiring, I'll try fitting that while I'm pissing about with it next.
I don't have a scope to test it but have a few things to investigate now.
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Just had a couple of hours spare so what did I do...
...read up on swapping a Lexus vvti V8 in :lol_hitting:
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Go on lead the way :icon_super: :icon_super:
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http://www.ebay.co.uk/itm/LS400-Engine-/200998382273?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2ecc6feac1
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stop it!
These are an easy-ish swap into an MX5 too, did look at doing it to mine, any excuse to keep it....
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After having left it over Christmas with the battery disconnected it now starts and doesn't have any SKIM codes stored :017:
Still barely running, chugging, bucking and almost stalling so I changed rotor, dist cap, leads and plugs for new and known good spares. No change, plugs all look ok, no obvious odd one out and all the grey ish colour they should be. Changed TPS back to old one, no change. Unplugged O2 while running, slight stumble then carried on as before. Smells like it's running very rich or not burning all fuel.
Getting some codes but very inconsistent, once cleared most don't come back. Last one was P1694, loss of communication with Transmission control unit.
Any ideas where to check next?
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Local scrap yard?
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Have you checked the fuel pressure? Should be around 45psi.
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No, do I need a proper test kit or can I do it any other way?
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Have you checked the fuel pressure? Should be around 45psi.
Just completed a test with the proper kit, only got 14/15 psi with ignition on and 22/23 psi at idle. Trying to increase throttle is tricky but it didn't seem to make any difference to pressure. I also checked if the pressure held and it does for at least 5 minutes which was the time quoted in the FSM for a leakdown test.
From this I'm thinking it's a knackered fuel pump. I am going to check for any kinks in the fuel line like it says i the manual but am suspecting fuel pump.
Some reassurance I'm going the right route would be nice, I don't want to spend £150 on a new fuel pump and not fix the problem.
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Not sure about the pump in an xj and if it's the same as a tj. When mine failed I did some googling an managed to just get the pump part itself from the local supplier. It ended up being listed for a Honda.
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maybe just maybe you could disable your in tank fuel pump and use a 'Facet' fuel pump along the chassis rail ......
Tis what is done on injected transplants into old stuff that had mech pumps on the block.
Some are adjustable for pressure as well........ facet pumps if powerful enough are about £30-50
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Yes, same as TJ, at least the late nineties TJs. I'd rather get a complete new standard unit but might get a good used one to test it will fix the issues. I prefer to keep it stock but will take a look at externals while I shop around.
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Are mk1 and mk2 pumps the same? If so I have a spare.
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No, the early ones are smaller, I think they changed the same time as the tanks changed from metal to plastic. I've ordered a second hand one now and will start the process of dropping the tank tomorrow.
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Replacement fuel pump fitted and fuel pressure is back, idle is sweet and it revs nicely.
:ace:
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Nice one James :icon_biggrin:
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Good one!
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:icon_super: Now you go out and abuse it again :icon_twisted:
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Tank, skid and rear bumper refitted and all seems good.
Big thanks the Dr Mike once again for the heads up on fuel pressure test when I was going mad looking at sensors :greggmo:
The cherry bomb sounds sweet now :icon_twisted:
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:icon_super: Now you go out and abuse it again :icon_twisted:
Planning quite a few events this year, first one March so got to get some of the more fun stuff sorted.
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nice one jay
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Tank, skid and rear bumper refitted and all seems good.
Big thanks the Dr Mike once again for the heads up on fuel pressure test when I was going mad looking at sensors :greggmo:
The cherry bomb sounds sweet now :icon_twisted:
:icon_super:
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We'll done James, tis a great feeling when things go well :steeringwheel: